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Figure 12.3.1. Ellipsoid and geoid

Vertical-control surveys establish elevations for a network of
reference monuments called benchmarks. Depending on accuracy
requirements, they have traditionally been run by either differential

leveling or trigonometric leveling. As previously stated, GPS can also
be used to establish vertical control, but the most accurate and widely
applied method is precise differential leveling.

VI. INDIVIDUAL WORK

Task 1. Complete the text with the words from the box and
translate it into Ukrainian.

distances, slope, depends on, horizontal line, the gradient.

Slope representation and measurement

Whenever a line is not horizontal, it has __________. The slope

can be uphill or downhill. A slope is the rise or fall of the land surface.
A slope is easy to recognize in a hilly area. Start climbing from the
foot of a hill toward the top, this is called a rising slope. Go downhill,

this is a falling slope.
Its steepness _________ the difference in height between its
points. The slope of the ground affects the measurement of
_________. Ground slope is also very important in the design of fish-

farms, since you can use it to reduce your construction costs. You need
to build bottom slopes in canals, to allow the water to move
by gravity; and in ponds, to allow good drainage. And you must build

slopes in the dikes for ponds and dams.
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